The present invention relates to tufted carpet floor covering materials which are conventionally constructed by stitching carpet yarn into a loosely woven sheet of material usually referred to as the primary carpet backing material. This material is normally woven from natural materials such as jute or synthetic materials such as polypropylene and polyethylene. Following stitching of the carpet yarn into the primary backing material, the product has an upper surface with a face of carpet yarn and an undersurface with rows of tuft loop backs of carpet yarn. In order to secure the carpet yarn in place in the primary backing, a layer of a suitable adhesive composition is then spread over the loop backs. This adhesive serves to secure the yarn in place within the primary backing material. In some forms of carpet construction a second woven layer of backing material is then placed on top of the primary layer of adhesive, which is on the back or undersurface of the carpet in order to finish the carpet product. This second woven layer is conventionally referred to as the secondary backing.
In other forms of carpet construction the adhesive composition is spread on the back or undersurface of the carpet product in sufficient quantities to adhere the loops of carpet yarn in place and provide an integral secondary backing. Often in these forms of construction the layer of adhesive composition coating the back is foamed to provide an additional cushion effect. In still other forms of construction, a layer of foam material is placed on top of a layer of adhesive which has been coated on the primary backing to finish the carpet product. The common feature of all forms of tufted carpet is the use of a suitable adhesive composition to secure the tuft loops in place and optionally secure additional layers of other materials to the carpet product.
Tufted carpet has been popular because of the inherent sound deadening features and also the attractive appearance and ease of maintenance for such floor coverings. However, tufted carpet, both residential and commercial, has long been recognized as a sink for odors. In addition to odors from normal dust and dirt, tufted carpet is highly susceptible to acquiring odors from feet, pets, cooking food, spills, smoke and mold and mildew. Carpet cleaners, e.g., vacuums, steam cleaners, spray foams, etc. have long been used to deodorize as well as clean. Relatively recently, carpet deodorizers were introduced to combat odors already in the carpets. These products were predominantly based on fragrances to mask the malodor. The products also contained various levels of sodium bicarbonate to actually deodorize the malodors in the carpet through neutralization and adsorption. None of these devices or products, however, were meant to be odor preventatives.
The deodorization properties of sodium bicarbonate are well-documented. Accordingly, sodium bicarbonate has been topically employed as a deodorant in refrigerators, carpets, personal deodorants and body powders, mouth rinses, aerosol air fresheners, cat litter additives, drain fresheners, etc. Additionally, sodium bicarbonate has a history of being a safe compound, e.g. it is classified as Generally Recognized As Safe--(GRAS), both when taken internally and applied externally to the skin.
Initial attempts at applying sodium bicarbonate as a powder as a permanent deodorizer in tufted carpet was unsatisfactory as the treated carpet would not withstand shipping and handling. Disadvantageously, the bicarbonate powder would accumulate in areas of the carpet and be highly visible and dusty upon installation. Additionally, the powder would be susceptible to removal by normal vacuuming and cleaning. Applying the sodium bicarbonate as a solution to the carpet surface overcame the accumulation and removal drawbacks, but was also highly visible as a powdery residue and also made the carpet feel stiff. Additionally, there were indications that the sodium bicarbonate was reacting with the acid dyes in the carpet and causing slight color changes.
Accordingly, it is an object of the present invention to provide a process which imparts to carpeting, during its manufacture, long term protection against odors developing from common household sources, such as, foot odor, pet odor, smoke odor and the like. This treatment should be resistant to normal vacuuming and steam cleaning and not detract from the aesthetics of the carpeting by unsightly visible accumulations.
This and other objects, features and advantages of the present invention will become apparent from reviewing the following description.